Vacuum-pump.



No. 845,738. :PATENT'ED MAR. 5, 1907.

' L. R. ALBBRGBR. VACUUM PUMP.

APPLICATION FILED APR-6. 1902.

THE NDRRIS PETERS cm, WASHINGTON, o. c.

Y-UNITED STATES PATENT OFFICE.

Louise. ALBERGER, or. GREENWIOH, CONNECTICUT, ASSIGNOR TO ALBER- GER CONDENSER. COMPANY, OF. NEW YORK, N. I, ACQRPORATIQN QF VACUUM -PUMPW Specification of Letters'Patentt Patented March 5, 1907.

To, all whom it. may concern.-

Be it knownthat I, LOUIS R .,ALB.E,RGER, a citizen, ofthev United States ofAmerica, and a; resident. of Greenwich, in the county of Fairfield' andv State of'Connecticut, have, invented'certainnew andlusefullmprovements I in-Vacuum-Pumps,ofwhichthe ollowingis This invention relates to vacuum pumps. Its object, is, to improve, the efiiciency of pumps of this class by reducing the leakage that. commonly occurs. between. thesurfaces Qfthe moving parts.

Itconsists in various, novel and useful features offconstruction, arrangement, andcom-- bination, among them that of two or more vacuum-cylinders, one withdrawingfrom the other for the purpose of minimizing the loss by leal iagev in the primary or, high-vacuum cylinder, and a. second feature, is that of a stufling-box for the pistonrod,valve-rod, or othermovingpart, which box has. an interior 7 Space. containing air or vapor at a pressure intermediate in degree between that in the cylinder andlthe, atmosphere; and the inventiOn further comprises numerous details and peculiarities, all substantially as will be hereinafter described. and claimed.

In the annexed draw ing, illustrating my invention, Figure 1 is. a longitudinal vertical section of my improved vacuum,- pump. Big. 2 is a right-hand end elevation of'one of the. cylinders with certain. parts shown in cross-section. h ig. 3 is an enlarged sectional detail of one ofthe automatic valves belonging to, thecylinders. 1: ig. 4 is a, plan view of the valve-seat;v

Like numerals of reference designate like parts throughout the difierent figures.

1 denotes the primary or high-vacuum cylinder of my improved vacuum-pump, and 2 the secondary or low-vacuum cylinder of the Same, said two cylinders being arranged either. in rectilineal alinement with. each other, as indicated in the draw ings, or in any other relative location which may be found suitable. In the cylinder 1 is a piston 3, and in the cylinder 2 is apiston 4, both pistons in the present example of the invention being on thesame piston-rod5. Itis not essential,

. how ever, that the. cylinders, pistons, and piston-rod should have; this specific, arrangeinent, and. I dio not wish to be restricted thereto, provided. the, same. results in. op era.-

tion can be attained by diiierently placing the parts. On the wall of each cylinder is; a valve-chest 6', containing a suitable suction slide-valveas, for instance, a D-val've 7 which controls ports 8' and 9, leading to opposite ends ofthe cylinder.

10 indicates a suction-pipe running from any chamber, apparatus, or other place from 'which air is to be exhausted and entering the side of the cylinder 1 'at the suction inlet-port 11, which inlet is situated between the inner terminals of the ports 8 and 9 and is susceptible of'being connected with one port or the other by means of' the suction-valve 7 In the valve-chest 6 near each end and between the chest and the cylinder is an automatic outlet-valve for the discharge of air from, the, cylinder, the discharge taking place into the chest 6, whence (in case of cylinder 1) it is, carried by the connecting-pipe 13 to the second cylinder 2, said pipe 13 so far as the, cylinder 2 is concerned being to all intents and purposes a suction-pipe and entering the cylinder 2 at a port 14 in like manner as the primary suction-pipe 1O enters cylinder lat the inlet-port 1 1. The suction slidevalves 7 of the; two cylinders have the same valve-rod 15, by means of which they are mechanically operated in unison when the general arrangement of the two cylinders is of the type illustrated in the drawing, said valve-rod 15 being actuated by an eccentric or by any other common and well-known means. The discharge from the second cylinder 2 is through automatic valves into valve-chest 6 and then into the dischargepipe 16, which leads out of the yalve-chest of the cylinder 2 in like manner as the connecting-p ipe 13 leads out of the valve-chest of the primary cylinder 1.

The detailed construction of the automatic outlet-valves and their seat is represented in Figs. and 4. 17 denotes a screw threadedbushing or ring, which screws into anopening' adjacent tothe port 8 or the port 9-, as the case may be, said bushing having spokes or radial arms that carry a bearing 18 at their center, into which is screwed a pin 19, having on its upper end a disk 20. The valve proper, 21, is perforated centrally to permit the passage of the screw-threaded pin 19 through it and is of suflicient size to cover the opening through the bushing 17, as shown in Big. 3. A spring 22 is tensioned between the valve 21 and the disk 20. Thus when the valve 21 opens to allow the discharge of air the spring 22 will be compressed, and the latter will act to close the valve when the expansive force of the air that opens it has been diminished below the power of the spring. When the air in advance of the moving piston opens the valve 21, it will escape past said valve, and if it be one of the valves belonging to the cylinder 1 the escaping air will pass into the suction-pipe 13, leading to the sec. ondary cylinder, while if it be one of the valves of the secondary cylinder the air will escape through the discharge 16 into the atmosphere or elsewhere.

The main object in employing two stages in a vacuum-producing pump is to minimize or reduce to the lowest possible degree the loss incident to leakage in the primary or high-vacuum cylinder. If the primary cylinder discharges into the suction of a second cylinder which is producing, say, a vacuum equal to five pounds absolute pressure (or twenty inches of vacuum) and the primary cylinder is producing a vacuum equal to, say, one pound absolute pressure (or twenty-eight inches of vacuum) or a difference of four pounds between the pressures in the twocylinders, then the leakage around the piston and through the valves of the primary cylinder will be that due to four pounds instead of that due to fourteen pounds of pressure,

' which would be the difference in case the primary cylinder discharged directly into the atmosphere. The efhciency is otherwise greatly increased from the fact that the clearance-space at the end of the stroke is filled with air at five pounds absolute pressure instead of fifteen pounds and upon the reversal of the stroke the expansion of the air is correspondingly reduced.

At the point where the piston-rod 5 passes through the head 12 of the primary cylinder 1 I employ an improved stuffing-box, which is in reality a double stufling-box and is particularly applicable to the piston-rods of dry vacuum or air pumps that handle air or vapors under a pressure below that of the atmosphere and in which little or no water can be allowed to enter the cylinder. This double stufiing-box has two packings 24 24, of soft fiber or other suitable similar packing material, separated by a hollow perforated s ool-piece 25, so that in the stuffing-box t ere is an interior cavity or recess. A pipe leads from this interior cavity of the stuffingbox to the suction-pipe 13, which runs between the two cylinders. Hence the opening in the hollow spool-piece 25 is in communication with a vacuum-producing apparatusto wit, the secondary or 1 ow-vacuum cylinder 2 and its pistonwhereby a pressure in the said hollow spool-piece is maintained below that of atmospheric pressure, but not necessarily as low as that produced by the primary vacuum-cylinder into which the piston-rod passes and to which the stuffing-box belongs. Any air that leaks from the atmosphere through the outer packing 24 into the intervening cavity 2.5 is removed by the secondary vacuum-pump and cannot reach the interior of the cylinder 1. Inasmuch as the difference between the pressure in cylinder 1 and in the stuffing-box spool is less than the difference between the pressure in said cylinder and the atmosphere, the leakage be tween the spool and the cylinder must necessarily be much less than if there were no intervening vacuum-space between the cylinder and the atmosphere. The result of this arrangement is that not only is the total amount of air that leaks in through the stufiing-box reduced, but the high-vacuum cylinder is guarded against a leakage of air that is particularly objectionable and that would cause a reduction of the efliciency of the machine.

As I have previously intimated, numerous modifications and changes in the construction and arrangement may be made without departing from the invention. It is not necessary that both cylinders should be arranged with their pistons on the same pistonrod and one cylinder withdrawing from the other; but they may be difierently placed, and the secondary cylinder may be an entirely separate machinethat is to say, an independently-driven machineif desired. The secondary cylinder may have a connection between its suction-pipe and the stuifingbox cavity, as shown, or may serve merely to remove air that leaks into the spool-piece through the outer packing without having any other connection with the high-vacuum cylinder.

Having thus described my invention, what I claim as new, and desire to secure by Letters Patent, is-

1. In a vacuum-pump, the combination of a primary cylinder and its piston, a secondary cylinder and its piston, a piston-rod common to the two pistons, a valve-chest for each cylinder, a suction-valve in each chest, a valve-rod common to the suction-valves, a suction-pipe leading from the primary cylinder to the secondary cylinder, and means for reducing air leakage into the primary cylinder, consisting of a stufiing-box on the pistonrod, said box having an interior space be-.

tween its packings, said space containing air or vapor at a pressure intermediate in degree between that in the cylinder and the atmosphere, and a pipe leading from said interior space to the suction-pipe which connects the cylinders.

2. In a vacuum-pump, the combination of a primary cylinder and its piston, a secondary cylinder and its piston, a piston-rod common to the two pistons, a valve-chest for each cylinder, a slide-valve in each chest, a valverod common to the slide-valves, and means for reducing air leakage into the primary cylinder, consisting of a stufling-box on the piston-rod, said box having two packings and a hollow perforated spool separating the packings so as to provide an interior cavity or recess containing air or vapor at a pressure intermediate in degree between that in the cylinder'and the atmosphere, and means for removing the air that leaks into the stuffingbox, consisting of a pipe leading from said inner space to the suction-pipe which connects the cylinders.

3. In a vacuum-pump, the combination of a primary cylinder and its piston, a secondary cylinder and its piston, a piston-rod common to the two pistons, a valve-chest for each cylinder, a suction-valve in each chest, a valve-rod common to the suction-valves, a suction-pipe for the secondary cylinder, a stuffing-box on the piston-rod having suitable packings separated by a spool pieceproviding an interior space contairnng a1r or vapor at a pressure intermediate in degree between that in the cylinder and the atmosphere, and a pipe leading from the spool-piece to the suction-pipe for the secondary cylinder.

4. In a vacuum-pump, the combination of a primarycylinder and its piston, a secondary cylinder and its piston, a valve-chest for -each cylinder, a suction-valve in each chest, a

suction-pipe leading from the primary cylinder to the secondary cylinder, and means for reducing air leakage into the primary cylinder, consisting of a stufling-box having an interior space containing air or vapor at a pressure intermediate in degree between that in the cylinder and the atmosphere, and a pipe leading from said interior space to the suction-pipe which connects the cylinders.

5. In a vacuum-pump, the combination of a primary cylinder and its piston, a secondary cylinder and its piston, means for operating the two pistons, a valve-chest for each cylinder, a suction-valve in each chest, means for operating the suction-valves, a suctionpipe leading from the primary cylinder to the secondary cylinder, and means for reducing air leakage into the primary cylinder, consisting of a stuffing-box on the piston-rod, said box having an interior space containing air or vapor at a pressure intermediate in degree between that in the cylinder and the atmosphere, and means providing a passage between said interior space and the suctionpipe which connects the cylinders.

6. In a vacuum-pump, the combination of a primary cylinder and its piston, a pistonrod for said piston, and means for reducing air leakage into the said cylinder, consisting of -a stuffing-box having an interior space containing air or vapor at a pressure intermediate in degree between that in the cylinder and the atmosphere, and means for removing the air from the stuffing-box, consisting in a secondary cylinder in communication with the said stufiing-box.

7. In a vacuum-pump, the combination of a primary cylinder, its piston, and a pistonrod for said piston, means for reducing air leakage into the primary cylinder consisting of a box on the pistonrod, the said box having an interior space containing air or vapor at a pressure intermediate in degree between that in the cylinder and the atmosphere, a secondary cylinder, its piston and piston-rod, a suctionipe leading from the primary cylinder to t e secondary cylinder, and means providing a passage from the box to said suction-pipe.

8. In a vacuum-pump, the combination of a primary cylinder its piston and piston-rod, means for reducing air leakage into the primary cylinderconsisting of a stuffing-box for the piston-rod, said box containing air or vapor at a pressure intermediate in degree between that in the cylinder and the atmosphere, a secondary cylinder, a suction-pipe therefor, and a pipe leading from said stufiingbox to said suction-pipe of the secondary cylinder.

9. In a vacuum-pump, the combination of a primary cylinder, its piston and piston-rod, means for reducing air leakage into the primary cylinder consisting of a stufling-box for the piston-rod, said box having an interior space containing air or vapor at a pressure intermediate in degree between that in the cylinder and the atmosphere, a secondary cylinder, its piston and piston-rod, a suction-pipe leading to said secondary cylinder, and a pipe leading from the interior space of the stufiingbox to the suction-pipe of the secondary cy inder, all arranged and operated substantially as set forth.

Signed at New York, N. Y., this 31st day of March, 1902.

LOUIS R. ALBERGER.

Witnesses:

NICHOLAS SELVAGGI, M. L. SHAY. 

